Ir non-contact temperature sensing in a dispenser

ABSTRACT

A dispensing system includes an optional pre-heat station configured to receive an electronic substrate, a dispense station configured to dispense material on the electronic substrate received from the optional pre-heat station, an optional post-heat station configured to receive the electronic substrate from the dispense station, and a non-contact sensor positioned above the electronic substrate on at least one of the optional pre-heat station, the dispense station, and the optional post-heat station.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Application Ser. No. 62/792,087 titled “IR Non-ContactTemperature Sensing in a Dispenser” filed on Jan. 14, 2019, which isherein incorporated by reference in its entirety, and claims priority toU.S. application Ser. No. 15/831,800, titled “Material TemperatureSensor for Stencil Printer” filed on Dec. 5, 2017, which is hereinincorporated by reference in its entirety.

BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure

The present disclosure relates to an apparatus and process fordispensing material, and more specifically to an apparatus and processfor dispensing solder paste in a dispenser.

2. Discussion of Related Art

There are several types of dispensing systems used to dispense preciseamounts of liquid or paste for a variety of applications. One suchapplication is the assembly of integrated circuit chips and otherelectronic components onto circuit board substrates. In thisapplication, automated dispensing systems are used for dispensing dotsof liquid epoxy or solder paste, or some other related material, ontocircuit boards. Automated dispensing systems are also used fordispensing lines of underfill materials and encapsulents, which may beused to mechanically secure components to the circuit board. Exemplarydispensing systems described above include those manufactured anddistributed by ITW EAE of Glenview, Ill. under the brand name CAMALOT®.

In a typical dispensing system, a pump and/or dispenser assembly ismounted to a moving assembly or gantry for moving the pump and dispenserassembly along three mutually orthogonal axes (X-axis, Y-axis, Z-axis)using servomotors controlled by a computer system or controller. Todispense a dot of liquid on a circuit board or other substrate at adesired location, the pump and dispenser assembly is moved along theco-planar horizontal X-axis and Y-axis until it is located over thedesired location. In one embodiment, the pump and/or dispenser assemblyis then lowered along the perpendicularly oriented vertical Z-axis untila nozzle/needle of the pump and dispenser assembly is at an appropriatedispensing height over the electronic substrate. The pump and/ordispenser assembly dispenses a dot of liquid, is then raised along theZ-axis direction, moved along the X-axis and the Y-axis directions to anew location, and is lowered along the Z-axis direction to dispense thenext liquid dot. In another embodiment, material is jetted from the pumpand dispenser assembly without lowering and raising the nozzle/needle ofthe pump and dispenser assembly. For applications such as encapsulationor underfilling as described above, the pump and dispenser assembly istypically controlled to dispense lines of material as the pump anddispenser assembly are moved in the X-axis and the Y-axis directionsalong the desired path of the lines.

The use of an IR temperature sensor to monitor the temperature of asupply cartridge of solder paste in a stencil printer is known,motivated by the need to ensure that the paste was up to the propertemperature to proceed with a print deposition. Similarly, theapplication of material temperature sensing in a pump and dispenserassembly of a dispensing system is known, motivated by the need toensure that material stored at a temperature lower than a properapplication temperature had indeed warmed to the proper temperature fordeposition.

SUMMARY OF THE DISCLOSURE

One aspect of the present disclosure is directed to a dispensing systemcomprising an optional pre-heat station configured to receive anelectronic substrate, a dispense station configured to dispense materialon the electronic substrate received from the optional pre-heat station,an optional post-heat station configured to receive the electronicsubstrate from the dispense station, and a non-contact sensor positionedabove the electronic substrate on at least one of the optional pre-heatstation, the dispense station, and the optional post-heat station.

Embodiments of the dispensing system further may include the non-contactsensor being positioned above the electronic substrate on the optionalpre-heat station to ensure that the electronic substrate is at a propertemperature before moving the electronic substrate to the dispensestation. The non-contact sensor may be mounted on an adjustablemechanism that moves towards and away from a target of the temperaturemeasurement. The non-contact sensor may be positioned above the dispensestation to ensure that the electronic substrate is at a propertemperature at the dispense station. The non-contact sensor may bemounted on an adjustable mechanism associated with the dispense station.The non-contact sensor may be positioned above the electronic substrateon the optional post-heat station to ensure that the electronicsubstrate is at a proper temperature at the optional post-heat station.The non-contact sensor may be mounted on an adjustable mechanism thatmoves towards and away from a target of the temperature measurement. Thenon-contact sensor may be an infrared temperature sensor.

Another aspect of the present disclosure is directed a dispensing systemconfigured to dispense a viscous assembly material on an electronicsubstrate. In one embodiment, the dispensing system comprises a conveyorconfigured to move electronic substrates through the dispensing system,a dispense station including a dispensing unit configured to dispenseviscous assembly material on an electronic substrate, and a sensorcoupled to the dispensing unit, the sensor being configured to measure atemperature of the electronic substrate.

Embodiments of the dispensing system further may include the sensorbeing a non-contact sensor. The non-contact sensor may be an infraredsensor. The non-contact sensor may be secured to the dispensing unit byan adjustable bracket. The adjustable bracket may be configured toorient the non-contact sensor at an angle with respect to an orientationof the electronic substrate.

Yet another aspect of the present disclosure is directed to a method ofprinting an assembly material on an electronic substrate. In oneembodiment, the method comprises: delivering an electronic substrate toa dispensing system; positioning the electronic substrate in a printposition; dispensing viscous assembly material on the electronicsubstrate; and measuring a temperature of the electronic substrate.

Embodiments of the method further may include providing temperaturefeedback of the electronic substrate as part of a temperature regulationsystem. Providing temperature feedback may include, when an electronicsubstrate has reached a desired target temperature, the temperaturecontrol system turns off the heat to the electronic substrate, and whenthe temperature drops below a low temperature limit, the temperaturecontrol system turns the heat on. Measuring a temperature of theelectronic substrate may be achieved by a sensor. The sensor may be anon-contact sensor. The non-contact sensor may be an infrared sensor.The method further may include positioning the non-contact sensor withrespect to the electronic substrate by an adjustable bracket.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of at least one embodiment are discussed below withreference to the accompanying figures, which are not intended to bedrawn to scale. The figures are included to provide an illustration anda further understanding of the various aspects and embodiments, and areincorporated in and constitute a part of this specification, but are notintended as a definition of the limits of any particular embodiment. Thedrawings, together with the remainder of the specification, serve toexplain principles and operations of the described and claimed aspectsand embodiments. In the figures, each identical or nearly identicalcomponent that is illustrated in various figures is represented by alike numeral. For purposes of clarity, not every component may belabeled in every figure. In the figures:

FIG. 1 is a schematic view of a dispensing system;

FIG. 2 is a perspective view of a dispensing system with packagingremoved to disclose a pre-heat station, a dispense station and apost-heat station;

FIG. 3 is a graphic user interface (“GUI”) of an infrared (“IR”) senseconfiguration graphic associated with the pre-heat station and thepost-heat station;

FIG. 4 is a GUI of an IR sense configuration graphic associated with thedispense station;

FIGS. 5 and 6 are GUIs of a process programming graphic;

FIGS. 7 and 8 are GUIs of a process monitoring graphic;

FIG. 9 is a flow chart of an operation of an IR sense command;

FIG. 10 is a GUI of an IR sense command graphic;

FIG. 11 is a GUI of a heat options graphic; and

FIG. 12 is a GUI of a power on heat controllers graphic.

DETAILED DESCRIPTION OF THE DISCLOSURE

For the purposes of illustration only, and not to limit the generality,the present disclosure will now be described in detail with reference tothe accompanying figures. This disclosure is not limited in itsapplication to the details of construction and the arrangement ofcomponents set forth in the following description or illustrated in thedrawings. The principles set forth in this disclosure are capable ofother embodiments and of being practiced or carried out in various ways.Also, the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. Any references toexamples, embodiments, components, elements or acts of the systems andmethods herein referred to in the singular may also embrace embodimentsincluding a plurality, and any references in plural to any embodiment,component, element or act herein may also embrace embodiments includingonly a singularity. References in the singular or plural form are notintended to limit the presently disclosed systems or methods, theircomponents, acts, or elements. The use herein of “including,”“comprising,” “having,” “containing,” “involving,” and variationsthereof is meant to encompass the items listed thereafter andequivalents thereof as well as additional items. References to “or” maybe construed as inclusive so that any terms described using “or” mayindicate any of a single, more than one, and all of the described terms.In addition, in the event of inconsistent usages of terms between thisdocument and documents incorporated herein by reference, the term usagein the incorporated reference is supplementary to that of this document;for irreconcilable inconsistencies, the term usage in this documentcontrols.

The present disclosure is directed to sensing not only the temperatureof the material to be deposited, but also the temperature of theelectronic substrate upon which the material is to be deposited. Forexample, it is well-known in the SMT assembly industry that theelectronic substrate in a dispenser is often preheated before depositionof underfill materials. Typical applications utilize what is known as apre-heat “chuck” (an area or zone for heating an electronic substrate toa pre-determined temperature), before the electronic substrate istransported into a dispense zone to receive the material to bedispensed. A problem with the preheat zone is that there is typicallyonly one feedback sensor to measure the temperature of the entirepre-heat chuck, which is typically 330 mm×250 mm. This feedback from asingle sensor generally senses the temperature at one location, and theresult is assumed to represent the temperature for the entire pre-heatzone, and does not necessarily reflect the actual temperature of aspecific location of interest, for example the temperature of a criticalcomponent. Furthermore, without feedback of the actual temperature ofspecific location of the electronic substrate, the time allocated topre-heat the electronic substrate is often selected to ensure that atleast a sufficient time has passed for the temperature of the electronicsubstrate to stabilize. This may mean that valuable time is wastedwaiting for an excessively long “sufficient” time period.

Embodiments of the present disclosure include a non-contact sensorpositioned above the electronic substrate on the pre-heat chuck toconfirm that the electronic substrate is indeed at the propertemperature before proceeding with the dispensing operation, without theneed to wait longer than necessary to ensure that the electronicsubstrate is up to temperature. By mounting the non-contact temperaturesensor over a particular location on the electronic substrate, theactual temperature of a critical location can be measured. Furthermore,by mounting the sensor to the dispensing unit (or other mechanism, suchas a vision probe in a printer) that can move in the X-axis and theY-axis directions over the electronic substrate, the temperature of anyspecific spot can be measured. The sensor also may be mounted on amechanism that moves towards and away from the target of the temperaturemeasurement or the target can move in the X-axis, the Y-axis, and theZ-axis directions relative to the sensor. Such a configuration permitsthe effective spot size of the sensor to be adjusted or tailored to theneeds of the application. For example, the sensor may be mounted on avertical stage, and oriented to look down at an electronic substrate. Bymoving the vertical stage and sensor lower and thus closer to theelectronic substrate, the temperature of a smaller localized spot may bemeasured. By moving the vertical stage and the sensor up and thusfurther from the electronic substrate, the temperature to be measuredmay effectively be averaged over a larger area. This can also beachieved by moving the target relative to the sensor to specificlocations and to achieve specific spot sizes. Such an arrangementpermits the sensing of a temperature averaged over a controllable sizeregion in which the size of the sensing area may be optimized for theapplication requirements. Thus, by mounting the sensor to a Z-axis stagewhich is in turn mounted to an X-Y positioning system, for example froma pump mounting bracket, both the location and the size of the spot canbe controlled.

By implementing the principles of the present disclosure, a depositionsystem can monitor the temperature of the materials to be dispensed bythe piece of equipment, as well as the temperature of critical locationson the electronic substrate upon which the material is to be dispensed,ensuring that all the participants in the deposition process are at thedesired temperature. Each of these measured temperatures may be utilizedto confirm that process variables are within a preset range prior toproceeding with the deposition process. Additionally (or perhapsalternatively), these measurements may be shared or stored for datacollection purposes, such as Statistical Process Control (SPC), whereinthe quality or yield of a process may be correlated with measuredvariables in a process, for the purposes of process optimization.

For purposes of illustration, embodiments of the present disclosure willnow be described with reference to a dispensing system, generallyindicated at 10, according to one embodiment of the present disclosure.Referring to FIG. 1, the dispensing system 10 is used to dispense aviscous material (e.g., an adhesive, encapsulent, epoxy, solder paste,underfill material, etc.) or a semi-viscous material (e.g., solderingflux, etc.) onto an electronic substrate 12, such as a printed circuitboard (“PCB”) or semiconductor wafer. The dispensing system 10 mayalternatively be used in other applications, such as for applyingautomotive gasketing material or in certain medical applications or forapplying conductive inks. It should be understood that references toviscous or semi-viscous materials, as used herein, are exemplary andintended to be non-limiting. The dispensing system 10 includes severaldispensing units, for example, first and second dispensing units,generally indicated at 14 and 16, respectively, and a controller 18 tocontrol the operation of the dispensing system. It should be understoodthat dispensing units also may be referred to herein as dispensing pumpsand/or dispensing heads. Although two dispensing units are shown, itshould be understood that more than two dispensing units may beemployed.

The dispensing system 10 may also include a frame 20 having a base orsupport 22 for supporting the electronic substrate 12, a dispensing unitgantry 24 movably coupled to the frame 20 for supporting and moving thedispensing units 14, 16, and a weight measurement device or weigh scale26 for weighing dispensed quantities of the viscous material, forexample, as part of a calibration procedure, and providing weight datato the controller 18. A conveyor system (not shown) or other transfermechanism, such as a walking beam, may be used in the dispensing system10 to control loading and unloading of electronic substrates to and fromthe dispensing system. The gantry 24 can be moved using motors under thecontrol of the controller 18 to position the dispensing units 14, 16 atpredetermined locations over the electronic substrate. The dispensingsystem 10 may include a display unit 28 connected to the controller 18for displaying various information to an operator. There may be anoptional second controller for controlling the dispensing units. Also,each dispensing unit 14, 16 can be configured with a Z axis sensor todetect a height at which the dispensing unit is disposed above theelectronic substrate 12 or above a feature mounted on the electronicsubstrate. The Z axis sensor is coupled to the controller 18 to relayinformation obtained by the sensor to the controller.

Prior to performing a dispensing operation, as described above, theelectronic substrate, e.g., the printed circuit board, must be alignedor otherwise in registration with a dispensing unit of the dispensingsystem. The dispensing system further includes a vision system 30,which, in one embodiment, is coupled to a vision system gantry 32movably coupled to the frame 20 for supporting and moving the visionsystem. In another embodiment, the vision system 30 may be provided onthe dispensing unit gantry 24. As described, the vision system 30 isemployed to verify the location of landmarks, known as fiducials, orcomponents on the electronic substrate. Once located, the controller canbe programmed to manipulate the movement of one or more of thedispensing units 14, 16 to dispense material on the electronicsubstrate.

In one embodiment, the dispense operation is controlled by thecontroller 18, which may include a computer system configured to controlmaterial dispensing units. In another embodiment, the controller 18 maybe manipulated by the operator. The controller 18 is configured tomanipulate the movement of the vision system gantry 32 to move thevision system so as to obtain one or more images of the electronicsubstrate 12. The controller 18 further is configured to manipulate themovement of the dispensing unit gantry 24 to move the dispensing units14, 16 to perform dispensing operations.

Referring to FIG. 2, a dispensing system is generally indicated at 200.As shown, the dispensing system 200 includes a dispense station,generally indicated at 202, a pre-heat station, generally indicated at204, provided upstream before the dispense station, and a post-heatstation, generally indicated at 206, provided downstream after thedispense station. The pre-heat station 204 defines a pre-heat zone, thedispense station 202 defines a dispense zone, and the post-heat station206 defines a post-heat zone of the dispensing system 200. A conveyor208 is provided to move an electronic substrate, such as substrate 12,from the pre-heat station 204 to the dispense station 202 and to thepost-heat station 206 (left-to-right in FIG. 2). As shown, the conveyor208 includes two lanes 208A, 208B to enable substrates to enter thedispense station more efficiently and at a greater rate. The pre-heatstation 204 is configured to heat the electronic substrate to anacceptable temperature for dispensing at the dispense station. Thepre-heat station 204 can be configured to increase the temperature ofthe electronic substrate between a range of 20° C. to 200° C. Thepost-heat station 206 is configured to reduce the temperature of theelectronic substrate prior to being passed along to another processingstation downstream from the dispensing system 200. As with the pre-heatstation 204, the post-heat station can be configured to reduce thetemperature of the electronic substrate between a range of 20° C. to200° C.

In one embodiment, the pre-heat station 204 and the post-heat station206 can be part of the dispensing system 200 that includes the dispensestation 202. In another embodiment, the dispensing system 200 can beconfigured to include the dispense station 202 only, and the pre-heatstation 204 and/or the post-heat station 206 can be separate units thatare assembled with the dispensing system, with the conveyor 208extending through all three stations.

The pre-heat station 204 includes an adjustable bracket, generallyindicated at 210, that is mounted on the conveyor 208 in an elevatedposition over the lanes 208A, 208B of the conveyor. As shown, theadjustable bracket 210 is positioned over the electronic substrate asthe electronic substrate travels along the lanes 208A, 208B of theconveyor 208 through the pre-heat station 204. For each lane 208A, 208B,an infrared sensor 212 is mounted on the adjustable bracket 210 and ispositioned to be directed toward the electronic substrate as theelectronic substrate travels under the adjustable bracket and theinfrared sensor on the lane of the conveyor. The adjustable bracket 210of the pre-heat station 204 can be configured to move each infraredsensor 212 in the X-axis, Y-axis and Z-axis directions.

In one embodiment, the adjustable bracket 210 includes a first railmember 214 that extends over lane 208A and a second rail member 216 thatextends over lane 208B. The first rail member 214 includes a firstsupport member 218 that is configured to ride along a track formed inthe first rail member. A first thumb screw 220 is provided to secure thefirst support member 218 to the first rail member 214 to lock the firstsupport member in place. The infrared sensor 212 is mounted on a freeend of the first support member 218. Similarly, the second rail member216 includes a second support member 222 that is configured to ridealong a track or slot formed in the second rail member. A second thumb224 screw is provided to secure the second support member 222 to thesecond rail member 216 to lock the second support member in place. Theinfrared sensor 212 is mounted on a free end of the second supportmember 222. The locations of the infrared sensors 212 can be adjusted byunlocking the thumb screws 220, 224 and moving the respective first andsecond support members 218, 222 to desired locations.

For each lane 208A, 208B, by mounting the infrared sensor 212 over aparticular location of the electronic substrate as the electronicsubstrate travels along the lane, the actual temperature of a criticallocation of the electronic substrate can be measured. The adjustablebracket 210 is configured to move each infrared sensor 212 towards andaway from the target of the temperature measurement in the Z-axisdirection and to position the infrared sensor in the X-axis and theY-axis directions. Such a configuration permits the effective spot sizeof the infrared sensor to be adjusted or tailored to the needs of theapplication. As mentioned above, the infrared sensor 212 can be orientedto look down at the electronic substrate. By manipulating the adjustablebracket 210 to lower the infrared sensor 212 closer to the electronicsubstrate, the temperature of a smaller localized spot may be measured.Conversely, by manipulating the adjustable bracket 210 to raise theinfrared sensor 212 away from the electronic substrate, the temperatureof a larger spot may be measured, thereby effectively being averagedover a larger area. Such a configuration enables the sensing of atemperature averaged over a controllable size region in which the sizeof the sensing area may be optimized for the application requirements.

Similarly, the post-heat station 206 includes an adjustable bracket,generally indicated at 230, which is identical to adjustable bracket 210of the pre-heat station 204, and is mounted on the conveyor 208 in anelevated position over the electronic substrate, such as electronicsubstrate 212, as the electronic substrate travels along the lanes 208A,208B of the conveyor through the post-heat station. For each lane 208A,208B, an infrared sensor 212, which is identical to the infrared sensorsused in the pre-heat station 204, is mounted on the adjustable bracket230 and is positioned to be directed toward the electronic substrate asthe electronic substrate travels under the adjustable bracket and theinfrared sensor. The adjustable bracket 230 of the post-heat station 206can be configured to move each infrared sensor 212 in the X-axis, Y-axisand Z-axis directions.

As mentioned, in one embodiment, the adjustable bracket 230 is identicalto adjustable bracket 210, and includes a third rail member 234 thatextends over lane 208A and a fourth rail member 236 that extends overlane 208B. The third rail member 234 includes a third support member 238that is configured to ride along a track or slot formed in the thirdrail member. A third thumb screw 240 is provided to secure the thirdsupport member 238 to the third rail member 234 to lock the thirdsupport member in place. The infrared sensor 212 is mounted on a freeend of the third support member 238. Similarly, the fourth rail member236 includes a fourth support member 242 that is configured to ridealong a track formed in the fourth rail member. A fourth thumb screw 244is provided to secure the fourth support member 242 to the fourth railmember 236 to lock the fourth support member in place. The infraredsensor 212 is mounted on a free end of the fourth support member 242.The locations of the infrared sensors 212 can be adjusted by unlockingthe third and fourth thumb screws 240, 244 and moving the third supportmember 238 and the fourth support member 242 to desired locations.

In one embodiment, the dispense station 202 further includes an infraredsensor 212 mounted on a carriage 250 that supports a dispensing unit 252or on the dispensing unit directly. Thus, the infrared sensor 212 ismoved by the gantry in the X-axis, Y-axis and Z-axis directions. Theinfrared sensor 212 can be operated to ensure that the electronicsubstrate as it is positioned within the dispense station 202 on lane208A or 208B of the conveyor 208 is at a suitable temperature fordispensing. As described above with respect to the pre-heat station 204and the post-heat station 206, the dispense station can be configured toincrease, maintain and/or decrease the temperature of the electronicsubstrate between 20° C. and 200° C.

Alternatively, in another embodiment, the infrared sensor 212 can bemounted on the vision system gantry, such as the vision system gantry 32of dispensing system 10, to move the infrared sensor in the X-axis,Y-axis and Z-axis directions. As with dispensing system 10, thedispensing system 200 can include more than one dispensing unit, withthe infrared sensor 212 being mounted on one of the dispensing units.

Thus, infrared sensing is used for non-contact temperature tracking overcomponents on the electronic substrate carried by the conveyor.Temperature sensing enables the operator to monitor and record thetemperature of the substrate in each process zone (up to six) within themachine. Pre-heat and post-heat dispense zones use the infrared sensorsmounted to the adjustable brackets in which the infrared sensors arepositioned and locked in place. The dispense zone(s) uses the infraredsensor mounted to the carriage and/or the dispensing unit so theconfiguration is flexible as to the location as set in the processprogram.

For each process zone, the operator selects a target temperature andtolerance range that the product needs to reach in order to beconsidered “ready.” “Ready” can mean that the product can move to thenext conveyor zone or if in the dispense zone “ready” for the dispenseprocess to begin. The other objective is to keep the substrate in the“ready” state, so when at temperature the machine automatically adjustsheat settings to keep the product within the desired tolerance range.

Referring to FIG. 3, which shows graphic user interface or GUI 300,infrared or IR sensing for electronic substrate temperature can beconfigured for all three zones, i.e., the pre-heat zone, the dispensezone, and the post-heat zone, through dedicated software. Within thesezones, IR sensing is achieved with the non-contact heat sensors andelectronic substrate clamping and can be configured for both single anddual-lane machine through execution software.

Referring to FIG. 4, which shows GUI 400, both pre-heat and post-heatsensing can be configured with non-contact heat sensing. The dispensestation configuration includes an option to enable IR sensing.

The operator can program temperature settings for each programindividually under a temperature tab while creating a new processprogram. The operator checks option “Use Temperature Settings fromProcess Program” to override the temperature settings from the machineconfiguration under the temperature tab. An alarm status changes from“Using Machine Config Parameters” to “Using Process Program Parameters.”If a process required heat, then a “Heat Required” option can be checkedto ensure no process program running without proper heat. The softwarecan be configured to issue an alarm in this case.

Referring to FIG. 5, which shows GUI 500, a maximum temperature limitfor IR sensing is 100° C. for all three zones, i.e., the pre-heat zone,the dispense zone, and the post-heat zone. The operator has an option toenable IR sensing ON/OFF for each zone within the process program.Default values for “Min. Temperature,” “Max. Temperature,” “Soak Time,”“Timeout” and “Polling Rate” are displayed for each zone, which arerepresented in Table 1.

TABLE 1 Min. Minimum electronic substrate temperature required for preheat, Temp. dispense and post heat zone Max. Maximum electronicsubstrate temperature required for pre heat, Temp. dispense and postheat zone Soak Time spent to maintain electronic substrate temperaturewithin Time range before transferring to next zone. Once soak timeexpired and next zone free electronic substrate will be transferred tothe next station (for pre heat/post heat). Timeout Timeout occurs if theelectronic substrate temperature does not fall within the programmedtemperature range with the programmed time limit. Benchmark will alarmif Timeout happens. Polling How often the IR sensor reads the electronicsubstrate Rate temperature

Referring to FIG. 6, which shows GUI 600, if IR sensing is disabled forthe pre-heat and/or post-heat zones, then the heating chucks associatedwith these zones should be heated up with a timer. A pre-heat and/orpost-heat duration timer is initiated to heat the chucks. Once the timerexpires, cycle station air should be switched back and forth ON/OFFbased on values entered.

The actual readings for the IR sensors are displayed real-time on theGUI through a data display panel as well as being a traceable MESfunction desired behavior of electronic substrate handling in each zoneas explained below.

In the pre-heat and/or post-heat zones, the process includes receivingan electronic substrate and start heating. Once at minimum temperature,a soak time is started. While soaking or waiting to move, heat is cycledON/OFF when the temperature hits a minimum or maximum predesignatedtemperature. Once the soak time has expired and the next zone is free,the electronic substrate is moved, and if the electronic substrate doesnot get in range before timeout time expires, then an alarm istriggered. For recovery, the steps are retry, abort, or release to nextzone. During an error state, if the operator does not perform any errorrecovery, the electronic substrate may heat up and reaches the maximumtemperature value. To avoid this effect, the software is configured topost an alarm, pause the machine, cycle the station air and keepmeasuring the electronic substrate temperature until the operatorperforms error recovery.

In the dispense zone, the process includes receiving the electronicsubstrate and measuring a temperature of the electronic substrate. Ifnot within range, heating is started until within range before timeoutexpires. Measuring the temperature is continued until within range. Ifwithin range, processing is started right away. At an end of thedispense cycle, the electronic substrate is moved to a next station assoon as possible. During error state, if the operator does not performany error recovery, the electronic substrate may heat up and reach amaximum temperature value. To avoid this effect, the software isconfigured to turn off station air, post an alarm, pause the machine,and keep measuring the electronic substrate temperature until theoperator perform error recovery. The process program can have multipleIR sense commands, and IR sensing is batched with dispense pass. Theability to sense electronic substrate temperature multiple times withindispense pass. There will only be a minimum temperature (no maximumtemperature). When an IR sense command is actuated, dispensing issuspended until a minimum temperature is reached. The alarm time appliesto each IR sense command as with pre-heat and post-heat sensing.

The infrared temperature sense command can be programmed at a desiredelectronic substrate location multiple times within the same processprogram on the electronic substrate. A chuck temperature, IR sensingstate timer, electronic substrate temperature, IR sensing state(ramping, soaking, maintaining), station air ON/OFF are listed on a datadisplay for easy process monitoring. Station air light on data displayturns green when ON and turns red when OFF. The status is displayed onlywhen process program is running.

Referring to FIG. 7, which shows GUI 700, when IR sensing is enabled,the timer tells the duration of the IR sensing state (i.e. how long thetemperature ramps up, soaking or maintaining). The timer resets when thestate changes.

Different states of IR sensing are shown in Table 2

TABLE 2 Ramping Electronic substrate arrived at the station and theelectronic substrate temperature is ramping up/down. Soaking Performsoaking for desired soak time. Cycle Air Maintaining electronicsubstrate temperature. Cycle the station air ON/OFF. Completed IRsensing operation is completed. Electronic substrate is transferred tothe next station (for preheat/post heat) Next command is ready to beexecuted (for dispense zone) Electronic substrate is transferred to thenext station (for dispense zone with “maintain heat”)

Referring to FIG. 8, which shows GUI 800, when “Maintain Temp” isselected by the operator, the IR sensor continue to read the temperatureand maintain the temperature within minimum and maximum by cycling theair. It acts the same as pre/post heat stations do presently.

Generally, when the electronic substrate comes into the pre heat zone,IR sensing state changes as follows:Ramping→Soaking→Completed→Maintaining.

Referring to FIG. 9, process 900 includes ensuring that the temperatureis maintained until the next station is free to accept electronicsubstrate. As shown, a determination is made at 902 as to whether adownstream station is free to accept an electronic substrate. If yes,then the IR sense command is complete at 904 and the operation ends. Ifno, then the temperature is detected at 906 by a non-contact sensor, anda determination is made at 906 as to whether the temperature is within apredetermined range. If yes, the process goes back to whether adownstream station is free to accept an electronic substrate. If no, airis cycled ON/OFF at 910 until the process goes back to whether adownstream station is free to accept an electronic substrate.

Referring to FIG. 10, which shows GUI 1000, the operator should placethe IR sense command in the main process program if “maintaintemperature” is required. If the IR sense command is located inside acall, this feature can be ignored. When using “pass,” the operatorshould assign the last pass to the IR sense command.

Referring to FIG. 11, which shows GUI 1100, when idle, all heat ispowered off. The operator can choose to power off all heat whichincludes chucks and needle heating based on programmed time in minutes.This functionality lies under a temperature tab in a machineconfiguration and works only in a dispense AUTOMATIC MODE. The operatorcan also check option to disable the power off heat function duringproduction run.

Referring to FIG. 12, which shows GUI 1200, at start-up, heatcontrollers are powered on. If the operator checks this option, thenheat controllers which includes up to six chucks and two needle heaterswill be powered on after startup. All heaters will start ramping up asleft enabled by the operator during last machine shut down only afterserver startup. If somehow the server startup is not automatic, thenheat controllers will not power on. In that case an operator mustmanually start the server to power on the heat controllers. Thisfunctionality lies under the temperature tab in the machineconfiguration and works in all dispense modes.

In one embodiment, a distance that the non-contact sensor is spaced fromthe electronic substrate depends on the type of non-contact sensorselected. For example, for one type of sensor, the sensor can be spacedfrom the electronic substrate a distance of 1 millimeters (mm) to 100mm. In one embodiment, a sensing spot size generated by the non-contactsensor corresponds to a spacing of the non-contact sensor from theelectronic substrate. Thus, by increasing a distance of the spacing ofthe non-contact sensor from the electronic substrate, the sensing spotsize is increased. Accordingly, a range for use within the print headassembly of embodiments of the present disclosure is a distance of 1 mmto 100 mm. In one embodiment, a distance of 25 mm is selected.

The non-contact sensor is configured to detect a temperature of theelectronic substrate to confirm whether the temperature is correct forthe particular application, using criteria pre-determined by a usersetup process in which the operator of the dispensing system inputssettings for the dispensing system before a dispense operation. Thenon-contact sensor is connected to the controller, and is configured toimmediately notify the operator if the electronic substrate is not readyfor deposition. Additionally, temperature data of the electronicsubstrate or multiple electronic substrates can be collected by thecontroller. The data collected can be fed back to the dispensing systemfor additional actions, or it can be sent to a data collection system,such as downstream machines or either internal or remote statisticalprocessing.

In certain embodiments, the non-contact sensor is an infrared sensor todetect the temperature of the electronic substrate. The infrared sensoris an electronic sensor that is configured to measure infrared lightthat radiates from an object positioned in a field of view of thesensor. Objects having a temperature above absolute zero emit heat inthe form of radiation. In a certain embodiment, the infrared sensor is aT-GAGE™ M18T Series Infrared Temperature Sensor offered by BannerEngineering Corporation of Minneapolis, Minn. The T-GAGE™ sensor is apassive, non-contact, temperature-based, sensor that is used to detectan object's temperature within a sensing window and output aproportional voltage or current, depending on the configuration of thesensor.

A non-contact sensor, such as non-contact sensor, positioned above theelectronic substrate on the pre-heat chuck can be utilized to confirmthat the electronic substrate is indeed at the proper temperature beforeproceeding with the dispensing operation, without the need to waitlonger than necessary to ensure that components of the system are at anadequate temperature. By mounting the non-contact sensor over aparticular location on the electronic substrate, the actual temperatureof a critical location can be measured. Furthermore, by mounting thesensor to the dispensing unit (or other mechanism, such as a visionprobe in a printer) that can move in the x-axis and y-axis directionsover the electronic substrate, the temperature of any specific spot canbe measure within the dispense station. The non-contact sensor also maybe mounted on a mechanism that moves towards and away from the target ofthe temperature measurement or the target can move in the x-axis, y-axisand z-axis directions relative to the sensor. Such a configurationpermits the effective spot size of the sensor to be adjusted or tailoredto the needs of the application. For example, the non-contact sensor maybe mounted on a vertical stage, and oriented to look down at anelectronic substrate. By moving the vertical stage and sensor lower andthus closer to the electronic substrate, the temperature of a smallerlocalized spot may be measured. By moving the vertical stage and sensorup and thus further from the electronic substrate, the temperature to bemeasured may effectively be averaged over a larger area. This can alsobe achieved by moving the target relative to the sensor to specificlocations and to achieve specific spot sizes. Such arrangements permitthe sensing of a temperature averaged over a controllable size region,wherein the size of the sensing area may be optimized for theapplication requirements. Thus, by mounting the sensor to a Z stage,which is in turn mounted to an X-Y positioning system, both the locationand the size of the spot can be controlled.

Additionally (or perhaps alternatively), measurements may be shared orstored for data collection purposes, such as statistical process control(SPC), wherein the quality or yield of a process may be correlated withmeasured variables in a process, for the purposes of processoptimization.

In another embodiment of the present disclosure, an infrared non-contacttemperature sensor is used to provide temperature feedback of theelectronic substrate temperature as part of a temperature regulationsystem. In particular, when an electronic substrate has reached adesired target temperature, commonly referred to as a set-pointtemperature, the temperature control system turns off the heat to theelectronic substrate. Subsequently, when the temperature drops below alow temperature limit, the temperature control system turns the heat on.In some embodiments, the operation of turning the heat on or off mayentail enabling or disabling power to the heaters. In other embodiments,this operation may entail enabling or disabling a heat transfermechanism. For example, in one embodiment of the present invention, airis circulated past a heated surface and then to the substrate. When theairflow is enabled, the transfer of heat from the heater to thesubstrate is enhanced. When the airflow is disabled, the transfer ofheat from the heater to the substrate is inhibited. This simplelimit-cycle approach may provide sufficient temperature control accuracyfor many applications.

In other embodiments of the present disclosure, an infrared non-contacttemperature sensor is used to provide temperature feedback of theelectronic substrate temperature as part of a closed-loop temperaturecontrol system. In such a system, the controller uses the measuredtemperature and the desired set-point temperature as inputs to a controlalgorithm. The algorithm may also have proportional control of theheater, which provides the ability to not just enable or disable heat,but rather to enable the heater at a number of smaller steps betweenfull on or full off. In one embodiment of the present disclosure, adigital proportional/integral/derivative controller, commonly referredto as a PID controller, uses the output of a PID algorithm, throughPulse-Width Modulation (PWM) means to vary the on/off duty cycle of aheater. This combination of a PID controller and digital proportionalcontrol of the heater can achieve temperature regulation that may bemore precise and more closely regulated that that achieved with a limitcycle regulator.

Having thus described several aspects of at least one embodiment of thisdisclosure, it is to be appreciated various alterations, modifications,and improvements will readily occur to those skilled in the art. Suchalterations, modifications, and improvements are intended to be part ofthis disclosure, and are intended to be within the spirit and scope ofthe disclosure. Accordingly, the foregoing description and drawings areby way of example only.

What is claimed is:
 1. A dispensing system comprising: an optionalpre-heat station configured to receive an electronic substrate; adispense station configured to dispense material on the electronicsubstrate received from the optional pre-heat station; an optionalpost-heat station configured to receive the electronic substrate fromthe dispense station; and a non-contact sensor positioned above theelectronic substrate on at least one of the optional pre-heat station,the dispense station, and the optional post-heat station.
 2. Thedispensing system of claim 1, wherein the non-contact sensor ispositioned above the electronic substrate on the optional pre-heatstation to ensure that the electronic substrate is at a propertemperature before moving the electronic substrate to the dispensestation.
 3. The dispensing system of claim 2, wherein the non-contactsensor is mounted on an adjustable mechanism that moves towards and awayfrom a target of the temperature measurement.
 4. The dispensing systemof claim 1, wherein the non-contact sensor is positioned above thedispense station to ensure that the electronic substrate is at a propertemperature at the dispense station.
 5. The dispensing system of claim4, wherein the non-contact sensor is mounted on an adjustable mechanismassociated with the dispense station.
 6. The dispensing system of claim1, wherein the non-contact sensor is positioned above the electronicsubstrate on the optional post-heat station to ensure that theelectronic substrate is at a proper temperature at the optionalpost-heat station.
 7. The dispensing system of claim 6, wherein thenon-contact sensor is mounted on an adjustable mechanism that movestowards and away from a target of the temperature measurement.
 8. Thedispensing system of claim 1, wherein the non-contact sensor is aninfrared temperature sensor.
 9. A dispensing system configured todispense a viscous assembly material on an electronic substrate, thedispensing system comprising: a conveyor configured to move electronicsubstrates through the dispensing system; a dispense station including adispensing unit configured to dispense viscous assembly material on anelectronic substrate; and a sensor coupled to the dispensing unit, thesensor being configured to measure a temperature of the electronicsubstrate.
 10. The dispensing system of claim 9, wherein the sensor is anon-contact sensor.
 11. The dispensing system of claim 10, wherein thenon-contact sensor is an infrared sensor.
 12. The dispensing system ofclaim 10, wherein the non-contact sensor is secured to the dispensingunit by an adjustable bracket.
 13. The dispensing system of claim 12,wherein the adjustable bracket is configured to orient the non-contactsensor at an angle with respect to an orientation of the electronicsubstrate.
 14. A method of printing an assembly material on anelectronic substrate, the method comprising: delivering an electronicsubstrate to a dispensing system; positioning the electronic substratein a print position; dispensing viscous assembly material on theelectronic substrate; and measuring a temperature of the electronicsubstrate.
 15. The method of claim 14, wherein measuring a temperatureof the electronic substrate is achieved by a sensor.
 16. The method ofclaim 15, wherein the sensor is a non-contact sensor.
 17. The method ofclaim 16, wherein the non-contact sensor is an infrared sensor.
 18. Themethod of claim 16, further comprising positioning the non-contactsensor with respect to the electronic substrate by an adjustablebracket.
 19. The method of claim 14, further comprising providingtemperature feedback of the electronic substrate as part of atemperature regulation system.
 20. The method of claim 19, whereinproviding temperature feedback includes, when an electronic substratehas reached a desired target temperature, the temperature control systemturns off the heat to the electronic substrate, and when the temperaturedrops below a low temperature limit, the temperature control systemturns the heat on.